The above patent addressed the need for architectural windows to allow for good light transmission while shielding against radio frequency (RF) energy. The significance of RF shielding for architectural windows is directly associated with the dramatic growth and widespread use of radio frequency emitting devices. Radio stations, microwave relay stations, televisions, computers, two-way radios, and many other electronic devices either use or transmit electromagnetic energy in the radio frequency range--from 100 Hz to 100 GHz.
The need for shielding in buildings has several bases. One such basis is the protection of electronic equipment from interfacing with the operation of other electronic equipment. An example would be in the operation of high energy RF emitting equipment (e.g. a ship's radar) which might penetrate a nearby building's outer shell and cause electronic error to occur in a digital computer system.
A second basis for shielding might involve the protection of people from RF energy, which in high doses causes tissues to heat, e.g. in the use of microwave ovens. In lower doses, other biological damage is possible.
A third need for shielding arises with concern for electronic spying--for political, economic or industrial advantage. This concern is justly based on the relative ease by which one can remotely (up to 2 mile away in some circumstances) monitor the information on a standard computer Cathode Ray Tube (CRT) screen.